35Half-life decay
A medicine has a half-life of 6 hours. A patient takes 80 mg. How much is left after 18 hours?
After 18 hours, 10 mg of the medicine is left. 18 hours is 3 half-lives, so the dose halves three times: 80 → 40 → 20 → 10 mg.
A medicine has a half-life of 6 hours. A patient takes 80 mg. How much is left after 18 hours?
After 18 hours, 10 mg of the medicine is left. 18 hours is 3 half-lives, so the dose halves three times: 80 → 40 → 20 → 10 mg.